1. Field of the Invention
The present invention is generally related design structures, and more specifically, design structures for monitoring and regulating the voltage supplied by a voltage regulation module to a processor in response to a dynamic VID.
2. Description of the Related Art
In the past, CPUs functioned on a static voltage. The static voltage supplied to a CPU could be monitored and easily compared to the expected voltage to make sure the supplied voltage was within a specified margin of error from the expected voltage. Now, CPUs are designed to operate on dynamic (variable) voltages driven by a voltage regulation module (VRM). A variable-voltage CPU outputs a dynamic “voltage identification” signal (VID) to the VRM in order to specify the voltage that the CPU requires at each moment. The VRM generates a dynamic voltage in response to the dynamic VID. The dynamic nature of the VID output presents unique challenges for monitoring the voltage to ensure proper regulation.
A microcontroller that is responsible for verifying that the CPU receives the correct voltage from the VRM must be able to compare the actual voltage with the voltage expected for the current VID. Accordingly, the microcontroller will first need to sense the voltage and convert the sensed voltage from an analog value to a digital value. While certain microcontrollers have a built-in analog to digital converter (i.e., an A/D converter), converting a voltage reading from an analog to digital value takes a considerably long amount of time (for example, milliseconds) in comparison with the timescale on which a VID may change (for example, microseconds). Accordingly, it is quite possible that the VID output to the VRM will change during an analog to digital conversion of the voltage being supplied to the CPU. Such a change in the VID will promptly cause a resulting change in the voltage and affect the analog to digital conversion. When this happens, the digital value is not representative of the voltage resulting from the VID.
Therefore, there is a need for an improved system and method for monitoring the voltage regulator module in order to verify that the CPU is receiving an actual voltage that is close to the expected voltage. It would be desirable if the system and method could be accomplished without disrupting the normal operation of the CPU and the VRM. It would be even more desirable if the system and method could be implemented without requiring any customized or expensive hardware components.